Step 1

Thaw your sheet of puff pastry dough (it usually takes about 40 minutes). You can also thaw it overnight in the fridge.

Step 2

Preheat oven to 400 degrees F. Line a baking sheet with parchment paper or lightly grease with cooking spray. Whisk together egg with 1 tsp cold water to make an egg wash. Roll out your puff pastry sheet to smooth ridges and make it slightly thinner. Cut out four squares roughly 5x5 inches in size. Place squares on baking sheet.Brush the squares lightly with egg wash. Place in the preheated oven to bake for 10-15 minutes until golden brown.

Step 3

While puff pastry is baking, fit your food processor with the blade attachment. Place fresh basil leaves inside along with ¼ cup of grated cheese, garlic clove, fresh lemon juice, and milk. Process until mixture is creamy, scraping the sides once to make sure all ingredients are processed. Reserve ¼ cup of grated cheese for garnish.

Step 4

Place a small saucepan on the stovetop. Melt butter in the pan on medium high heat. Add flour to the melted butter and whisk to dissolve.

Step 5

Continue whisking until the flour mixture turns a sandy-brown color.

Step 6

Slowly add basil mixture from food processor, whisking constantly to blend.Bring to a simmer for about 2 minutes to melt the cheese and thicken the sauce. Reduce heat to low, season with salt and pepper to taste. Keep sauce warm until ready to serve, whisking periodically to break up any skin that develops on the surface.

Step 7

When puff pastry is finished baking, remove from oven and set baking sheet on the counter to rest. Turn heat up to 450 degrees F.

Step 8

In skillet, heat olive oil over medium high heat till hot (not brown or smoking). Add the fillets to the skillet—if your fillets are skin-on, place the fillets skin side up, meat side down.

Step 9

Sear them on one side for 2-3 minutes until you see a brown crust forming on the meat.Without flipping the salmon, transfer the skillet to the oven and let it cook for 7-9 more minutes to desired doneness. Remove salmon from the oven. Use an oven mitt, that skillet handle will be HOT! If you cooked your fillets skin-on, peel off the cooked skins and discard before proceeding.

Step 10

Assemble your salmon on serving plates. For each serving, place a piece of puff pastry on the plate. Ladle 3-4 tbsp of sauce onto the top of the puff pastry. Place seared salmon fillet on top of the sauce. Sprinkle the salmon with about ½ tbsp of grated cheese, or more to taste. Top with two fresh tomato slices and a sprig of fresh basil. Serve.